The Architeuthis Principle
When winter came, Snape took out his heavy woolen cloak, a pair of thick black gloves, the soft scarf of deepest green Minerva knitted him one Christmas. The drifts were piled high against the sides of the castle, snow stinging against his face as he walked. Snape merely hunched deeper into his cloak, buried his gloved hands in his sleeves. When he had hiked all the way out to the lake, Snape carefully cast an unfreezing charm on the water.
Then he fed the squid.
Why, he wasn't sure. By all rights, the squid was Hagrid's responsibility, and Flitwick, though Snape hated to admit it, was far better at charms work than he. But Flitwick never ventured out into such weather -- far too cold for a man of his size -- and Hagrid was forbidden from charms of any kind. So, once again, the task fell to Snape, because someone had to take responsibility for these things, and no one else made the move to do so.
Snape sometimes thought these sorts of things always fell to him. Voldemort. Potter.
Squid.
Once his task was completed, Snape stood by the water's edge for a few moments, rubbing his gloved hands together and watching his breath steam in the frigid air. Snow whirled around his solitary figure, the wind whipping his scarf about like a snake. The lake was silent. Snape nodded, once, and turned to leave.
A large, sinuous tentacle slid out of the water after him. Snape turned back. The tentacle, its bottom lined with faint pink suckers, wavered in the air in front of him. Beneath the freshly unfrozen water, two luminous, unblinking eyes shone out at him.
Snape raised an eyebrow. "Yes?"
The squid curled its tentacle into a languid fist and brushed Snape's cheek with it, whisper-soft. Then squid and tentacle alike were gone, leaving behind only ripples at the surface and the faint smell of roses in the air.
Snape touched his cheek. Smiled. Then he turned and walked back to the castle, swallowed by the whirling snow. Where he stood, only snow drifts remained.